1. Field of the Invention
This invention relates to very effective and novel antiperspirant compositions in an acceptable cosmetic base. More specifically, this invention relates to essentially anhydrous antiperspirants in the form of solid sticks which have the ability to maintain their physical structure over a long time and still produce an elegant feel when applied to the skin without any adversities, e.g. tack or drag; the skin is left feeling smooth and soft while retaining antiperspirant activity.
2. Discussion of the Relevant Art
Numerous stick antiperspirant compositions are known, and have been published in a variety of cosmetic journals and by suppliers of cosmetic ingredients. Those skilled in the art have accepted the fact that anhydrous antiperspirant stick systems are more advantageous to market and have good consumer acceptance primarily due to the ease of application to the skin, good cosmetic aesthetics and an acceptable degree of effectiveness. Previous to the development of anhydrous stick systems numerous water based systems were developed in which the active astringent salts were solubilized in a thickened or gelled composition. This is exemplified in U.S. Pat. Nos. 2,732,327; 2,857,315; 3,255,082; and 3,928,557. The water based systems are difficult to apply to the skin and their consistency and effectiveness are questionable.
Antiperspirant stick systems consisting of low molecular weight monohydric alcohols in conjunction with polyhydric alcohols as described in U.S. Pat. No. 4,137,306, issued to Rubino, have the advantage of quicker drying rates, but the residue of the polyhydric alcohols in combination with the atringent salts produces a high degree of tack and their effectiveness is limited to the type and amount of astringent salts that could be incorporated therein. It should be noted that sticks of this nature have never been successfully marketed.
Anhydrous stick compositions that suspend the aluminum salt in a hydrophobic matrix as described in U.S. Pat. No. 4,049,792, issued to Elsnau, make use of waxy materials and a long chain of fatty esters to form a stick that delivers the active astringent salts to the skin. Preparations made by these teachings are rather greasy and they envelop the active astringent salt for long periods of time preventing their maximum performance. To alleviate this inherent negative characteristic volatile silicone fluids replaced the lesser volatile long chain fatty esters as described by U.S. Pat. No. 4,126,679, issued to Davy et al. Davy teaches the advantage of incorporating a volatile, non-staining liquid such as cyclic dimethylpolysiloxanes, referred to as volatile silicones, as a carrier in combination with various types of waxes for the active astringent salts in an antiperspirant stick composition. Similar antiperspirant stick compositions containing volatile silicones are described by U.S. Pat. Nos. 4,151,272, 4,280,994 and 4,435,382.
Although the volatile silicone based antiperspirant stick compositions are effective and highly aesthetic they may contain up to 80% by weight of volatile silicone. The use of such large amounts of volatile silicone make preparations prepared very expensive. Attempts to decrease or replace the volatile silicone content in anhydrous antiperspirant stick composition to reduce cost is constant and is exemplified in U.S. Pat. Nos. 4,425,328 and 4,229,432. These types of compositions, however, are more oily with longer dry out rates and are less appealing to the consumer.
In order to overcome the shortcoming of known anhydrous antiperspirant sticks the present invention replaces the volatile silicone with non-polar volatile liquid ingredients, in part or in total. There is a need for such a replacement to lower the cost of producing antiperspirant sticks while still giving the consumer an effective highly aesthetic product. Inexpensive ingredients, having the same desirable attributes of volatile silicone, namely, low irritation, low degree of fabric staining, good volatility, compatibility with an array of non-polar organic compounds while providing good feel to the skin, is not available in anhydrous antiperspirant compositions that allow for effective and safe products. Ingredients may be available which exhibit one or more of these desired attributes but the combination of these attributes, for use in preparing anhydrous antiperspirant systems, has not been demonstrated. Ingredients fulfilling these requirements, which have not been used previous to this invention, in any anhydrous antiperspirant composition of any form are volatile isoparaffin liquids.